Photographic color film and process of making same



United States Patent 3,515,557 PHOTOGRAPHIC COLOR FILM AND PROCESS OF MAKING SAME Victor F. H. Chu, East Brunswick, and Jacob Quentin Umberger, Holmdel, N.J., assignors to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Apr. 12, 1965, Ser. No. 447,573 Int. Cl. G03c 7/32 US. C]. 96-74 9 Claims ABSTRACT OF THE DISCLOSURE A photographic color film comprising a support, a light-sensitive gelatino-silver halide layer which rs essen tially sensitive to one primary region of the visible spectrum and contains a lipophilic color coupler dispersed in a continuous phase of a hydrophilic color coupler containing at least one solubilizing carboxylic or sulfonic group, both of said color couplers being capable of forming the same dye color which is complementary to said primary color region, at least one of the color couplers being polymeric and the ratio of said hydrophilic to lipophilic coupler being about 30 to 300 parts of hydrophrlrc to about 100 parts of lipophilic color coupler.

This invention relates to color photography and more particularly to multilayer films for color photography. Still more particularly this invention relates to multilayer color photographic films, the light sensitive layers of which contain lipophilic and hydrophilic color couplers in separate phases. In another aspect, this invention relates to processes for the manufacture of multilayer color films comprising light sensitive layers containing lipophilic and hydrophilic color couplers in separate hases. P The art of color photography is highly developed, and many photographic systems for recording images in color are known. The most widely accepted system at the present time is the so-called color reversal process of substrative color photography. Integral-coupler multilayer color reversal films are well known and comprise, basically, a film support having coated thereon in order, a redsensitive gelatino-silver halide layer containing a cyan color coupler, a green-sensitive gelatino-silver halide layer containing a magenta color coupler, a yellow filter layer, and, finally, a blue-sensitive gelatino-silver halide layer containing a yellow color coupler. Other auxiliary layers such as antihalation layers, separator layers and antiabrasion layers may also be present in the film element. Color negative films are similar to reversal but have an additional requirement-colored couplers for color correction or masking. The art is replete with various types of chemical structures which have been found useful as color couplers in multilayer color reversal films. There are many requirements for integral color couplers, viz, Where the color couplers are incorporated in the lightsensitive layers rather than in the processing solutions. One of the basic requirements is that they be nondifiusible, that is, they should not migrate from the layer in which they are incorporated to a contiguous layer. Diffusion or wandering is characteristic of many of the known color couplers in their simplest molecular configuration. Attempts to prevent diffusion have been pursued in several directions. One is to attach weighting groups, e.g., large fatty acid groups to the color coupler or color former molecule. Another method is to encapsulate the molecule in a polymer or high-boiling solvent which is water insoluble but dispersible in the hydrophilic colloid carrier, for the silver halide, e.g., gelatin. Still another Patented June 2, 1970 ice method is to attach the color coupler molecule to the linear chain of a synthetic polymer which is either compatible with or dispersible in the colloid carrier for the silver halide. As a general premise, couplers which may be made nondiffusible by one of the above methods fall into two very important groups; namely, water-soluble or hydrophilic and oil-soluble or lipophilic. Hydrophilic couplers, ordinarily have one or more water-solubilizing groups such as sulfonic or carboxylic groups in the molecule and the lipophilic couplers are devoid of such groups. As is Well known in the art of manufacturing multilayer color films utilizing these two types of color formers, the presence or absence of these polar groups has a profound effect on the physical characteristics of the layers in which they are incorporated. Even more important, in many cases the hydrophilic or lipophilic characterization can affect the sensitometric nature which may or may not be desirable in the quality of the final color reproduction. For example the prior art acknowledges the fact that nondifiusible hydrophilic color couplers containing the above mentioned acid groups have a strong tendency to react with gelatin when they are in solution. This raises the viscosity of the total emulsion mixture and requires a large amount of gelatin and water in relation to the amount of color coupler in order to provide a suitable coating medium. This in turn tends to slow the drying and increase the thickness of the coated layer. As a result, there may be a decrease in the dye density which can be obtained from a given coated layer thickness. The presence of such hydrophilic color couplers also has a strong influence on lowering the setting point of the coated emulsion layer thus adding to the problems of manufacture. A further very serious problem is that of brittleness in the coated layer particularly in view of the fact that it is desirable to coat thin layers containing a high proportion of color coupler in order to obtain images having high color density and good resolution. One attempt to produce layers having good flexibility is by dispersing polymeric latices, e.g., polyethylacrylate, in the gelatin emulsion layers, but layer thickness is thereby increased. One further disadvantage in using hydrophilic couplers is that they tend to influence the development rates. For example some magenta color couplers cause development acceleration whereas some cyan couplers retard development.

The utilization of lipophilic or water-insoluble type color couplers also presents problems. In this case it is necessary to carry out complicated dispersion procedures in order to properly incorporate a sufficient amount of the color couplers in the gelatino-silver halide emulsion layers. The procedures generally involve using a high-boiling solvent for the color coupler and a low-boiling solvent in conjunction therewith. The color coupler solutions are then dispersed in aqueous gleatin, the low-boiling solvent removed and the dispersion is added to the silver halide emulsion. Here, as in the case of hydrophilic couplers, large quantities of gelatin and high-boiling solvent in relation to the amount of color coupler are necessary in order to adequately disperse the couplers in the layers. Again, layers coated from such dispersions are too thick for good resolution. In addition, the presence of highboiling solvents in quantities sufiicient to dissolve the couplers seriously decreases the hardness of the coated layers. Thus, instead of obtaining multilayer elements having layers which are too brittle and subject to cracking on flexing as in the case of using hydrophilic couplers, there are obtained multilayer elements having layers which are excessively soft and subject to surface abrasion. If the amount of high-boiling solvent is reduced to overcome excessive softness, the reactivity of the color coupler to the oxidation products of the color developer produced during development may be reduced. In addition crystallization of the coupler may occur at low ratio dispersions. A further disadvantage in utilizing dispersed lipophilic color couplers is that of graininess which is, of course, particularly noticeable when projecting cine films.

It has now been found that the above difi'iculties can be overcome and high-quality single layer or multilayer color films having good physical characteristics and capable of producing high-quality color images can be obtained by utilizing both lipophilic and hydrophilic color couplers which form the same color in combination as a dispersed phase in a continuous phase system. More specifically, a substantially water-insoluble lipophilic coupler is preferably dissolved in a low-boiling solvent with or without a small amount of high-boiling solvent and dispersing the solution in a gelatino-silver halide emulsion containing a water soluble color coupler, it is possible to obtain films having thin, hard coatings of 0.0005 inch or less which are flexible, and can be developed to give colored images having good dye density and high resolution.

The low-boiling solvents are those which generally are volatile near the boiling point of water and preferably below it. Exemplary of such solvents are methyl, ethyl, propyl and butylacetates; methyl propionate; ethyl and butyl formate; methylene chloride; nitromethane and nitroethane. Other low-boiling solvents are known in the art.

The amount of low-boiling point solvent required depends upon the solubility of the lipophilic color coupler in the solvent under normal atmospheric conditions. The amount of such solvent is usually no more than that needed to place the desired amount of lipophilic color coupler into the aqueous silver halide emulsion and to produce fine dispersions.

The ratio of the two types of couplers may vary over a wide range but in general the hydrophilic coupler may be used in amounts of at least 30 to 300 and preferably from 50 to 200 parts per 100 parts of the lipophilic couplers. The two types of couplers may be chosen from either the monornolecular type containing weighting groups or the polymeric type as described above. Among the high-boiling solvents which may be used with the lipophilic couplers are those having a double-bonded or semi-polar oxygen in their structure and boiling point above 200 C. They are particularly useful because of their plasticizing action on gelatin and hydrophilic couplers. Of this type there may be mentioned esters such as phthalates; N,N-dialkylarnides; sulfones; phosphate esters, e.g., tributyl phosphate; N-alkylated urethanes and mixtures thereof. Of course, there are many other suitable compounds of this type. However, the use of these highboiling solvents is optional because surprisingly, it has been found that lipophilic couplers, particularly those monomolecular types which contain large weighting groups have a plasticizing action on the gelatino-silver halide emulsion system. It then requires only the use of low-boiling solvents to effect dissolution and dispersion of the lipophilic color coupler in the emulsion. The amount of high-boiling solvent may very from to 100 parts per 100'parts of lipophilic coupler.

The preparation of standard color photographic emulsions are well known to those skilled in the art. The combination of the hydrophilic and lipophilic color couplers does not change the amount of color coupler needed in the emulsion.

The invention will now be illustrated by reference to the following examples.

EXAMPLE I This example illustrates the improvement in flexibility in a typical cyan color coupler-containing gelatin layer using a mixture of lipophilic and hydrophilic couplers as compared to using a hydrophilic color coupler alone.

To an aqueous gelatin solution containing 120 parts of gelatin there was-added, with stirring, 60 parts of a 4 hydrophilic cyan color coupler prepared by copolymerizing one mole of the monomer:

with one mole of maleic anhydride. This gelatin solution was coated on a polyethylene terephthalate film support to give a dried layer having a thickness of 0.00032 inch.

A dispersion was made using a lipophilic cyan color coupler having the formula;

n @fio ounomn The coupler in an amount of 6.5 grams was dissolved in 37.5 mils of ethyl acetate heated to 150 F. The solution was dispersed by means of a Waring blendor into 300 mls. of a 5% aqueous gelatin solution containing 10 mls. of a 10% aqueous solution of an alkylated sodium naphthalene sulfonate as a surfactant. The temperature of the mixture was maintained at 150 F. during the blending operation. Heating to 190 F. removed the ethyl acetate. A sufficient amount of this mixture and also of the hydrophilic cyan color coupler copolymer described above were used to make a dispersion containing:

The resulting dispersion was coated on the polyethylene terephthalate film support to give a dried layer thickness of approximately 0.00032 inch. Both coatings were sea-- soned under room conditions for several weeks and then subjected to the wedge-brittleness test described by P. Z. Adelstein in Journal of Photographic Science and Engineering, vol. 1, No. 2, October 1957, pages 63-68 under conditions of 10% relative humidity. The emulsion crack diameter for the gelatin layer containing the hydrophilic cyan color coupler alone was 0.39 inch while that of the gelatin layer containing the mixture of hydrophilic and lipophilic couplers was 0.23 inch. A gelatin layer containing 60 parts of the lipophilic coupler, only, per parts of gelatin and coated to give a dried layer of 0.00033 inch in thickness showed a tendency for the color-coupler particles to aggregate excessively during color development as evinced by graininess pattern seen on 8 mm. color projection.

EXAMPLE II Example I was repeated except that in the case of gelatin containing the hydrophilic coupler alone there was dispersed in the gelatin 20 parts of tributyl phosphate. In the case of the mixed couplers the lipophilic coupler was dispersed by using 20 parts of tributyl phosphate for dissolution in place of the ethyl acetate. In both cases the dispersions were accomplished by means of a Waring blendor. No heating was required since ethyl acetate was absent. The crack diameter of the hydrophilic couplergelatin-tributyl phosphate layer was 0.25 inch while that of the gelatin layer containing lipophilic and hydrophilic couplers and tributyl phosphate was 0.18 inch.

EXAMPLE III To an aqueous gelatin solution containing parts of gelatin there was added with stirring 60 parts of the hydrophilic magenta color coupler made by copolymerizing 1 mole of a color coupler monomer having the formula:

l o-NH-o-(s=crn 1 l C-CuHai The coupler in an amount of 7.5 grams was dissolved in 7.5 rnls. of tributyl phosphate and 30.0 mls. of ethyl acetate at a temperature of 150 F. The solution was added to 300 mls. of a 5% aqueous gelatin solution containing mls. of a 10% aqueous solution of the surfactant disclosed in Example I. The temperature of the mixture 'was maintained at 0 F. while being thoroughly blended with a Waring blendor to form a fine dispersion of the lipophilic color coupler in gelatin. A sufiicient amount of this mixture and also of the hydrophilic magenta color coupler copolymer described above were used to make a dispersion containing:

Parts Gelatin 120 Hydrophilic color coupler 40 Lipophilic color coupler 2O Tributylphosphate EXAMPLE IV This example will illustrate a comparison of the flexibility of a conventional color reversal film containing no flexibilizing agents, a color reversal film containing polymer latices as flexibilizing agents as described in assignees Chu, Firestine and Umberger, U.S. Ser. No. 113, 000 filed May 29, 1961, US. Pat. 3,211,552, Oct. 12, 1965, and color reversal films containing mixtures of lipophilic and hydrophilic color couplers.

(A) A color reversal film was prepared comprising the following:

(l) A cellulose triacetate photographic 'film base support having a conventional substratum and coated thereon a non-halation layer comprised of 7 mg./dm. of bone gelatin and 3.5 mg./dm. of a colloidal silver dispersion absorbing light of all visible wave lengths.

(2) A gelatino-silver bromo-iodide emulsion layer sensitive to blue and red light containing 3.4 mole percent silver iodide and 96.6 mole percent silver bromide and containing a sufiicient amount of the hydrophilic cyan copolymeric color coupler of Example I to give a color former coating weight of 9 mgJdm. with 18 mg./dm. of gelatin and 34 mg./dm-. of silver halide calculated as silver bromide.

(3) A separator layer comprised of a solution of bone gelatin containing normal additives, saponin surfactant plus chrome alum hardener, coated over the cyan layer at a coating weight of 20 rug/dm. of gelatin.

(4) A gelatino-silver bromo-iodide emulsion layer sensitive to blue and green containing 3.4 mole percent silver iodide and 96.6 mole percent silver bromide and containing the hydrophilic magenta copolymeric color coupler of Example III above in an amount to give a coating weight of 9.6 mg/dm. and 17 mg./dm. of gelatin and 32 mg./dm. of silver halide.

(5) A gelatin colloidal silver intermediate layer for absorbing blue light coated at 10 mg./dm. of gelatin and 1.3 mg./dm. of yellow colloidal silver.

(6) A gelatino-silver bromo-iodide emulsion layer sensitive to blue light containing 3.4 mole percent silver iodide and 96.6 mole percent silver bromide and containing a hydrophilic benzoylacetanilide yellow color'formerly prepared by transacetalization of parts of low viscosity 99% hydrolyzed polyvinyl alcohol with parts of m-benzoylacetamidobenzaldehyde ethylene glycol acetal and 50 parts of o-sulfobenzaldehyde in an ethanol-water reaction medium with p-toluenesulfonic acid to pH 1.7 as acetalization catalyst in the manner taught in McQueen US. 2,513,190 and coated to give a color former coating weight of 25 mg./dm. and a gelatin coating weight of 10 mg./dm. and a silver halide coating weight of 25 mg./dm.

(7) A gelatin antiabrasion layer of coating 10 mg./dm. bone gelatin and 1.5 mg./dm. of an ultra-violet absorber derived from 2,2-disulfo-4-4-diaminostilbene. The total calculated thickness of the layers was 0.0005 inch.

(B) A color reversal film was prepared as described above but with the addition of 12 mg./dm. of polyethylacrylate to the cyan layer, 6 mg./dm. to the magenta layer and 15 mg./dm. to the yellow emulsion layer all in the manner described in Example III of the above disclosed Chu, Firestine and Umberger application. The total thickness of the layers was calculated to be about 0.00065 inch.

(C) A color reversal film was prepared as described in (A) above except that in the red sensitive layer there was introduced for each 120 parts of gelatin 40 parts of the hydrophilic cyan color coupler, 20- parts of the lipophilic cyan color coupler and 20 parts of tributyl phosphate as described in Example II above. In the greensensitive layer there was introduced per 120 parts of gelatin, 40 parts of the hydrophilic magenta color coupler, 20 parts of the lipophilic magenta color coupler and 20 parts of tributyl phosphate as described in Example III above. In the blue sensitive layer there were introduced per 20 parts of gelatin, 40 parts of the hydrophilic yellow color coupler disclosed in (6) above, 20 parts of a lipophilic yellow color coupler having the formula:

rrrrooomco-Q NHCOCHzCO- and 20 parts of tributyl phosphate. The coating weights of combined color formers and of the gelatin in the emulsion layers were of the same order as in (A) as was the total layer thickness. The flexibilities of the three color films were compared in terms of their crack diameters following the test procedure described in Example 1 above. Film A was found to have a crack diameter of 0.73 inch, film B with the polyethylacrylate addition gave a crack diameter of 0.33 inch and film C using mixtures of lipophilic and hydrophilic couplers gave a crack diameter of 0.25 inch. When tested for resolving power as in Example V which follows, films A and C showed 90 lines per millimeter whereas the thicker emulsion B with noncoupling latex resolved 75 lines per millimeter.

. EXAMPLE V This example illustrates the superior results obtained in utilizing lipophilic and hydrophilic polymeric color (A) A color reversal film was prepared as described in (A) of Example IV except that the film support was 0.004 inch thick and constructed as disclosed in Example IV of Alles, US. Pat. 2,779,689 and the final structure of the film had the following characteristics:

Coupler, Gelatin, Silver halide rug/din. mg./ 1m.

Antiabrasion Yellow, mgJdmfi. 17 11 Yellow filter layer, as described in Ohu et al.,

U.S. Pat. 3, 182,029, May 4, 1965 10 Magenta, 13 mg./dm. 7 9 Separator, 3.9 mg./dm. of the aluminum salt of aurin tricarboxylic aoid Cyan, 21 mg./dm. Non halation layer- Support duced per parts of gelatin, 20 parts of the hydrophilic yellow copolymeric color coupler obtained by copolymerizing 1 mole of the yellow color coupler monomer:

and 1 mole of acrylic acid and 40 parts of the lipophilic yellow copolymeric color coupler obtained by copolymerizing 1.0 mole of the above monomer with 1.5 moles of Z-ethylhexyl acrylate. The resulting lipophilic yellow color coupler copolymer was introduced into the gelatino-silver halide emulsion in the same manner as the above lipophilic cyan color coupler copolymer.

The three silver halide emulsions were so constructed and coated that the quantities of silver halide calculated as silver bromide, total lipophilic and hydrophilic color coupler and gelatin were of approximately the same coating weight as in the color film A above.

The above films were tested for flexibility in the manner described in Example I with the result that film A showed a crack diameter of 0.7" and film B showed a crack diameter of 0.3".

Samples of films I and H were tested for resolution by giving them a white light exposure on an Eggert Resolvometer, described in Proceedings of the Royal Photographic Society Centenary Conference, London (1953), p. 292 and processed by reversal as described below, with all solutions and washes being at 80 F.:

H 6 minutes 2 minutes. 3 8-4. 2

3 minutes" 4 minutes 8. 0-8. 6

1 minute..-

2 minutes" 7. 6-8. 0

6minutes 12 Vletting-hardener 2 minutes 8. O-8. 8 13 Dry with 1.5 moles of ethyl acrylate. The lipophilic color coupler was introduced into the gelatino-silver bromoiodide emulsion by first dissolving 400 grams of the copolymer in 4000 ml. ethyl acetate and 120 mls. of di-isobutyl phthalate and introducing this solution with high speed stirring into an aqueous gelatin solution containing 120 grams of gelatin, 7000 ml. of distilled water and 320 ml. of a 10% aqueous solution of sodium lauryl sulfate. The ethyl acetate was removed by heating to give a fine dispersion of the lipophilic polymer in aqueous gelatin. Enough of this dispersion was used to give the above ratio in the final gelatino-silver bromoiodide emulsion. In the green-sensitive emulsion layer there was introduced per 80 parts of gelatin, 30 parts of the hydrophilic magenta copolymeric color coupler of Example III and 30 parts of the lipophilic magenta copolymeric color coupler obtained by copolymerizing 1 mole of the magenta color coupler monomer:

O: -C 2 a with three moles of ethyl acrylate. The resulting lipophilic magenta color coupler copolymer was introduced into the silver halide emulsion in the same manner as the above lipophilic cyan color coupler copolymer.

In the blue sensitive emulsion layer there was intro- 50 Black and white developer:

The processing solutions have the following formulations:

Grams Sodium hexametaphosphate 1.00 Sodium sulfite (anhyd.) 60.00

p-Methylaminophenol sulfate 5.00 Sodium hydroxide 1.00 Hydroquinone 2.00 Sodium carbonate (Mono) 50.00 Potassium iodide (0.1%) 10.00 Sodium bromide 2.00 Sodium thiocyanate 1.25 6-nitrobenzimidazole (0.5%) 7.00 Water to make 1.0 liter.

Color developer:

p-Aminodiethylaniline hydrochloride 5 .00 Sodium sulfite (anhyd.) 5.00 Sodium hexametaphosphate 1.00 Sodium bromide 0.50 Sodium hydroxide 1.00 Sodium carbonate 10.00 Potassium iodide (0.1%) 10.00 Benzyl alcohol 6.00

Water to make 1.0 liter.

Short stop:

Chrome alum 30.00 Water to make 1.0 liter.

Bleach:

Sodium bromide 30.0 Sodium sulfate 45.0 Potassium ferrocyanide 123.0 Water to make 1.0 liter.

Fixer:

Sodium thiosulfate (anhyd.) 115.0 Sodium sulfite 9.0

'Water to make 1.0 liter. Hardener:

Formalin20.00 ml.

Water to make 1.0 liter.

It was observed that 115 lines/mm. could be resolved for both films.

EXAMPLE VI This example illustrates the use of a hydrophilic cyan polymeric color coupler in conjunction with a lipophilic colored color coupler in a dispersed phase for the purpose of color correction which is useful in color negative films.

A lipophilic colored color coupler was prepared by dissolving 10 grams of the color coupler:

i -NH- C 1511 7 in a solution comprising 750 ml. of ethyl alcohol, 250 ml. of water and 100 ml. of 3 N sodium hydroxide. In 750 ml. of water there was dissolved 20 grams of the diazonium salt IQEN 2.014 8 02 11 O e CzHs 2 The above color coupler solution was added slowly with stirring to the diazonium salt solution and the pH was lowered to 4.5 to 5.0 with acetic acid. A dye precipitate formed which was recovered yielding about 15 grams of orange colored color coupler in the form of an oil.

In 17.5 ml. of 2 parts of d-ibutyl phthalate and 1 part of tributyl phosphate there was dissolved 6 ml. of the orange colored color coupler oil. This solution was heated to 120 F. and added to 300 ml. of a aqueous gelatin solution containing a surfactant and thoroughly dispersed by means of a Waring blendor.

To a gelatino-silver bromo-iodide emulsion as described in (A) (2) of Example IV there was added suflicient amounts of the hydrophilic cyan polymeric color coupler disclosed in Example I and the above lipophilic orange colored color coupler dispersion to provide for each 120 parts of gelatin in the emulsion, 30 parts of each of the lipophilic and hydrophilic couplers together with 80 parts of the above 2:1 high-boiling solvent. The emulsion was coated on a support at a silver halide coating weight of 20 mg./dm. The layer along with a similar control containing only the hydrophilic coupler was exposed in an intensity scale sensitometer with a Wratten #25 filter and developed for 5 minutes in the following color developer:

N,N diethyl p-phenylenediamine hydrochloride 5.0

grams Sodium sulfite (anhyd.)4.0 grams Sodium carbonate (mono)l0.0 grams Sodium salt of ethylene diaminetetraacetic acid-2.0

grams 6-nitro-benzimidazole (0.5% soln.)7.0 ml.

Potassium bromide0.5 gram 10 Borax-40.0 grams Potassium iodide (0.1% soln.)-10.0 m1. 3 N sodium hydroxide-23.0 ml. Polyethylene oxide .(Av. M.W. 4000- grams Water to make 1.0 liter After development, the elements were then processed as in steps 6 through 13 of 'Example V. After washing and drying, the gamma of the control at 436 m was +0.07 when the gamma at 644 m was adjusted to +1.0. The gamma of the green image from the mixed color coupler element at 436 me was 0.10 (due to masking) when EXAMPLE VII This example illustrates the incorporation of lipophilic and hydrophilic color couplers into a gelatino-silver halide emulsion by means of an anionic surface active color coupler. In a solution (A) of 250 ml. n-propyl acetate and 25 ml. tributyl phosphate there was dissolved 25 grams of the lipophilic cyan coupler disclosed in Example I. To 1000 ml. aqueous solution (B) containing grams of the hydrophilic copolymer of Example I there was added 250 ml. of an aqueous solution containing 50 grams of the anionic surface active color coupler having the formula:

Solution (A) was added to solution ,(B) at 100-105 F. and thoroughly dispersed by means of a high speed homomixer. The resulting dispersion of 3 types of cyan couplers was added to a gelatino-sil-ver bromoiodide in the manner taught by the above examples and could be used in the manufacture of extremely thin, flexible high definition photographic color films.

EXAMPLE VIII This example illustrates the use of anionic surface active couplers to disperse and incorporate into gelatino silver halide emulsions lipophilic polymeric couplers which were found to be very soluble in solvents such as organic esters. These uniquely soluble lipophilic polymers are prepared by addition polymerization of a coupler where the color-coupling group Q is attached to a polymerizable vinyl group via the connecting bivalent radial A taken from O- and 0 II ....o

with at least an equimolar amount of a noncoupling comonomer from the esters of acrylic, methacrylic, and maleic acids. This example will also demonstrate that the development rate of a coupling emulsion can be adjusted by varied distribution of coupling function between the hydrophilic and lipophilic emulsion phases.

Coatings of 25 mg./dm. of silver halide were prepared from emulsions of composition:

(A) 120 parts bone gelatin, 60 parts of the hydrophilic cyan naphthol polymeric coupler of Example I, 188 parts silver bromoiodide (97 mole percent Br and 3% I).

(B) 120 parts bone gelatin, 45 parts of the lipophilic cyan naphthol polymeric coupler of Example V, film B, dispersed as in that example but employing 15 parts of the color coupler l S OsNa as the anionic surfactant in place of the noncoupling suriactant of that example, 188 parts silver bromoiodide.

(C) 120 parts bone gelatin, 60 parts of the hydrophilic magenta polymer of Example III, 188 parts silver bromoiodide.

.(D) 120 parts bone gelatin, 188 parts silver bromoiodide.

Films A, B, C and D were exposed in a sensitometer and processed in the first or black-and-white developer of Example V. It was observed that the rate of development of silver in film A was retarded, relative to the control D, presumably due to the naphthal structure of the hydrophilic coupler. In film B with the majority of the naphthol now in the lipophilic dispersed phase, the development inhibition was lessened. Film C exhibited rapid development suggesting that this hydrophilic polymer coupler accelerates the development of silver.

EXAMPLE IX A color reversal film was prepared as described in (A) of Example IV except that the blue sensitive emulsion (6) contained per 120 parts of gelatin, 117 parts of benzoylacetanilide yellow color former shown in (6) and 685 parts of the yellow color former formed by polymerizing 1 mole of the monomer, p-methacrylaminebenzoylacetanilide and 2 moles of ethyl acrylate. The lipophilic coupler was dispersed by dissolving in a 168/ 14-0 ethanol/water solution at pH 11.35 and adjusting the pH to 6.3 after mixing the color formers. The emulsion was coated to give a total color former coating weight of about 24 mg./dm. a gelatin coating weight of 20 mg./dm. and a silver halide coating weight of 28 mgJdn-L A color reversal film control was made as described in (A) of Example IV except that the color former coating weight was 27 mg./dm. the gelatin was 15 mg./dm. and silver halide 28 mg./dm. The flexibility tests gave a crack diameter greater than 0.90 inch for the control and only 0.44 inch for the above film containing the combination of lipophilic and hydrophilic couplers in the yellow layer.

A further advantage to the process of this invention can be explained by the fact that the hydrophilic cyan copolymer of Example I was found to retard first or black-and-white development of emulsions containing it. This produced a serious problem in multilayer reversal films due to inadequate removal of cyan, usually termed highlight clean-out in red picture areas. By dispersing the cyan coupler in the lipophilic phase this problem was removed with improvement in the brightness of red scene areas.

As will be apparent to those skilled in the art, the

general premise of utilizing a dispersed phase lipophilic compound in a continuous phase of a hydrophilic compound is applicable to other aspects of photographic color film elements than to the incorporation. of color couplers. For example one may incorporate a hydrophilic polymeric color coupler in a continuous phase and a lipophilic color coupler dispersed by means of a soaplike weighted color coupler containing anionic groups which have surfactant characteristics. In addition, the invention may be used for the incorporation of both lipophilic and hydrophilic filter dyes and ultraviolet absorbing dyes and stabilizers in emulsion layers and filter layers which can bring about improvements in definition, color rendition and aging stability. The process of the invention may also be used to incorporate dyes in photographic color films which are used to form color images by the catalytic or dye bleach-out system. It will also be evident that the invention is applicable to any of the vast number of color couplers which may be obtained in both lipophilic and hydrophilic forms. The invention is not limited to gelatin layers or to gelatino-silver halide emulsion layers. It may also be used in silver halide systems utilizing other natural or synthetic colloids. As will be apparent from the examples the invention may not only be used for color reversal systems but can be just as readily utilized in conventional negative-positive systems of subtractive color photography.

The mixed hydrophilic-lipophilic couplers of this invention lessen the need for exceedingly fine dispersions of the lipophilic coupler since it comprises only part of the total image-forming coupler. Thus the need for ethyl acetate as auxiliary to the high-boiler for dispersion is lessened. Thus the safety hazard, cost and complexity of removing ethyl acetate can be avoided.

Also the mixed couplers of this invention permit formation of neutral-colored developed dyes images. They permit control of relative rates of dye development in the hydrophilic and lipophilic phases via control of the amount of oil in the droplets and solvent such as benzyl alcohol in the color developer.

This invention allows the achievement of an optimum balance between emulsion thinness and flexibility with no loss in resolution in the resulting color images. In other words it combines the flexibility of the dispersed oil-droplet system of lipophilic color coupler incorporation with the high definition of compatible or continuous phase hydrophilic color coupler systems without the disadvantages of excessive softness of the dispersed systems and the brittleness of the continuous phase systems. A further advantage flowing from the invention is that the black-and-white development rates for each of the constituent layers, yellow, cyan and magenta in color reversal films can be much more uniform by adjustment in each layer of the ratio hydrophilic to lipophilic couplers.

What is claimed is:

1. A thin, flexible multilayer photographic color film comprising a support bearing three silver halide layers and a yellow filter layer which have a total thickness no greater than 0.0005 inch and are so disposed and sensitized that each silver halide layer is essentially sensitive to a difierent primary color region of the visible spectrum, each of said silver halide layers containing a hydrophilic color coupler containing at least one solubilizing carboxylie or sulfonic group in a continuous phase and a lipophilic color coupler devoid of such groups dispersed in the continuous phase, both of said couplers form the same dye color which is essentially complementary to the primary color that exposes the silver halide in the individual layer, at least one of said color couplers being polymeric and having a vinyl chain of atoms with recurring color coupler groups attached to units of the chain of atoms, and the ratio of said couplers being about 30 to 300 parts of hydrophilic coupler to about parts of said lipophilic coupler.

2. A multilayer photographic color film as defined in claim 1 where each of said silver halide layers contains up to 100 parts of high-boiling point plasticizer to about 100 parts of said lipophilic coupler.

3. A photographic color film comprising a support, a light-sensitive gelatino-silver halide layer which is essentially sensitive to one primary region of the visible spectrum and contains a lipophilic polymeric color coupler having a vinyl chain of atoms with recurring color coupler groups attached to units of the chain of atoms, said coupler being dispersed in a continuous phase of an anionic surfactant which is a hydrophilic color coupler, both of said color couplers being capable of forming the same dye color which is complementary to said primary color region and the ratio of said hydrophilic to lipophilic coupler being about 30 to 300 parts of hydrophilic to about 100 parts of lipophilic color coupler.

4. A photographic color film comprising a support, a light-sensitive gelatino-silver halide layer which is essentially sensitive to one primary region of the visible spectrum and contain a lipophilic polymeric color coupler having a vinyl chain of atoms with recurring color coupler groups attached to units of the chain of atoms, said couple being dispersed in a continuous phase of a hydrophilic color coupler and an anionic surfactant which is a hydrophilic color coupler, all of said color couplers being capable of forming the same dye color which is complementary to said primary color region and the ratio of said hydrophilic to lipophilic coupler being about 30 to 300 parts of hydrophilic to about 100 parts of lipophilic color coupler.

5. A process for preparing a color photographic emulsion which comprises stirring a hydrophilic color coupler containing at least one carboxylic or sulfonic group with an aqueous gelatin solution containing silver halide which is sensitive to a primary color region of the visible spectrum, dispersing into another aqueous gelatin solution a lipophilic color coupler free from solubilizing groups dissolved in an organic solvent having a boiling point less than the standard boiling point of Water, and mixing said solutions together to give a ratio of about 30 to 300 parts of said hydrophilic color coupler to about 100 parts of said lipophilic color coupler, both of said color couplers being capable of forming the same color dye which is complementary to the color region sensitivity of said silver halide, and at least one of said color couplers is polymeric and having a vinyl chain of atoms with recurring color coupler groups attached to units of the chain of atoms.

6. A process as defined in claim Where said lipophilic color coupler is dissolved in a mixture of said organic solvent and a high-boiling point liquid plasticizer capable of dissolving said lipophilic coupler.

7. A process for preparing a multilayer photographic color film which comprises making three separate hydrophilic-lipophilic color couplers containing silver halide emulsions as defined in claim 5 where each separate emulsion is sensitized to a different primary color of the visible spectrum, coating each of said emulsions and a yellow filter layer in the desired order on the same surface of a support and drying said element at a temperature greater than the boiling point of said low-boiling solvent.

8. A process as defined in claim 5 where the total thickness of said coated layers is no greater than 0.0005 inch.

9. In a process for preparing a multilayer photographic color film having a yellow filter layer and three silver halide layers each essentially sensitive to a primary color region of the visible spectrum the improvement of adding a hydrophilic color coupler containing at least one solubilizing carboxylic or sulfonic group as a continuous phase and a lipophilic color coupler devoid of such groups, dispersing it in the continuous phase of each of said silver halide layers in combined amount to give the desired color density in each layer, at least one of said color formers being polymeric and having a vinyl chain of atoms with recurring color coupler groups attached to units of the chain,'said color couplers being capable of forming the same dye color which is complementary to the color region sensitivity of the silver halide layer in Which the couplers are placed and the ratio of couplers to one another being about 30 to 300 parts of hydrophilic coupler to about parts of lipophilic coupler.

References Cited UNITED STATES PATENTS 2,322,027 6/1943 Jelley et a1. 2,801,170 7/1957 Vittum et al. 2,852,381 9/1958 Minsk et al 9697 3,249,431 5/1966 Jaeken 96-9 FOREIGN PATENTS 42,938 4/1964 Japan. 4,293 4/1964 Japan.

GEORGE F. LESMES, Primary Examiner J. P. BRAMMER, Assistant Examiner US. Cl. X.R. 

